/*
 * Copyright (C)  Tony Green, Litepal Framework Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.litepal.crud;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.litepal.crud.model.AssociationsInfo;
import org.litepal.exceptions.DataSupportException;

import android.content.ContentValues;
import android.database.sqlite.SQLiteDatabase;

/**
 * This is a component under DataSupport. It deals with the saving stuff as
 * primary task. All the implementation based on the java reflection API and
 * Android SQLiteDatabase API. It will persist the model class into table. If
 * there're some associated models already persisted, it will build the
 * associations in database automatically between the current model and the
 * associated models.
 *
 * @author Tony Green
 * @since 1.1
 */
class SaveHandler extends DataHandler {

    /**
     * Initialize {@link org.litepal.crud.DataHandler#mDatabase} for operating database. Do not
     * allow to create instance of SaveHandler out of CRUD package.
     *
     * @param db The instance of SQLiteDatabase.
     */
    SaveHandler(SQLiteDatabase db) {
        mDatabase = db;
    }

    /**
     * The open interface for other classes in CRUD package to save a model. It
     * is called when a model class calls the save method. First of all, the
     * passed in baseObj will be saved into database. Then LitePal will analyze
     * the associations. If there're associated models detected, each associated
     * model which is persisted will build association with current model in
     * database.
     *
     * @param baseObj Current model to persist.
     * @throws java.lang.reflect.InvocationTargetException
     * @throws IllegalAccessException
     * @throws NoSuchMethodException
     * @throws IllegalArgumentException
     * @throws SecurityException
     */
    void onSave(DataSupport baseObj) throws SecurityException, IllegalArgumentException,
            NoSuchMethodException, IllegalAccessException, InvocationTargetException {
        String className = baseObj.getClassName();
        List<Field> supportedFields = getSupportedFields(className);
        Collection<AssociationsInfo> associationInfos = getAssociationInfo(className);
        if (!baseObj.isSaved()) {
            analyzeAssociatedModels(baseObj, associationInfos);
            doSaveAction(baseObj, supportedFields);
            analyzeAssociatedModels(baseObj, associationInfos);
        } else {
            analyzeAssociatedModels(baseObj, associationInfos);
            doUpdateAction(baseObj, supportedFields);
        }
    }

    /**
     * The open interface for other classes in CRUD package to save a model
     * collection. It is called when developer calls
     * {@link org.litepal.crud.DataSupport#saveAll(java.util.Collection)}. Each model in the collection
     * will be persisted. If there're associated models detected, each
     * associated model which is persisted will build association with current
     * model in database.
     *
     * @param collection Holds all models to persist.
     * @throws java.lang.reflect.InvocationTargetException
     * @throws IllegalAccessException
     * @throws NoSuchMethodException
     * @throws IllegalArgumentException
     * @throws SecurityException
     */
    <T extends DataSupport> void onSaveAll(Collection<T> collection) throws SecurityException,
            IllegalArgumentException, NoSuchMethodException, IllegalAccessException,
            InvocationTargetException {
        if (collection != null && collection.size() > 0) {
            DataSupport[] array = collection.toArray(new DataSupport[0]);
            DataSupport firstObj = array[0];
            String className = firstObj.getClassName();
            List<Field> supportedFields = getSupportedFields(className);
            Collection<AssociationsInfo> associationInfos = getAssociationInfo(className);
            for (DataSupport baseObj : array) {
                if (!baseObj.isSaved()) {
                    analyzeAssociatedModels(baseObj, associationInfos);
                    doSaveAction(baseObj, supportedFields);
                    analyzeAssociatedModels(baseObj, associationInfos);
                } else {
                    analyzeAssociatedModels(baseObj, associationInfos);
                    doUpdateAction(baseObj, supportedFields);
                }
                baseObj.clearAssociatedData();
            }
        }
    }

    /**
     * Persisting model class into database happens here. But first
     * {@link #beforeSave(org.litepal.crud.DataSupport, java.util.List, android.content.ContentValues)} will be called to
     * put the values for ContentValues. When the model is saved,
     * {@link #afterSave(org.litepal.crud.DataSupport, java.util.List, long)} will be called to do stuffs
     * after model is saved. Note that SaveSupport won't help with id. Any
     * developer who wants to set value to id will be ignored here. The value of
     * id will be generated by SQLite automatically.
     *
     * @param baseObj         Current model to persist.
     * @param supportedFields List of all supported fields.
     * @throws java.lang.reflect.InvocationTargetException
     * @throws IllegalAccessException
     * @throws NoSuchMethodException
     * @throws IllegalArgumentException
     * @throws SecurityException
     */
    private void doSaveAction(DataSupport baseObj, List<Field> supportedFields)
            throws SecurityException, IllegalArgumentException, NoSuchMethodException,
            IllegalAccessException, InvocationTargetException {
        ContentValues values = new ContentValues();
        beforeSave(baseObj, supportedFields, values);
        long id = saving(baseObj, values);
        afterSave(baseObj, supportedFields, id);
    }

    /**
     * Before the self model is saved, it will be analyzed first. Put all the
     * data contained by the model into ContentValues, including the fields
     * value and foreign key value.
     *
     * @param baseObj         Current model to persist.
     * @param supportedFields List of all supported fields.
     * @param values          To store data of current model for persisting.
     * @throws java.lang.reflect.InvocationTargetException
     * @throws IllegalAccessException
     * @throws NoSuchMethodException
     * @throws IllegalArgumentException
     * @throws SecurityException
     */
    private void beforeSave(DataSupport baseObj, List<Field> supportedFields, ContentValues values)
            throws SecurityException, IllegalArgumentException, NoSuchMethodException,
            IllegalAccessException, InvocationTargetException {
        putFieldsValue(baseObj, supportedFields, values);
        putForeignKeyValue(values, baseObj);
    }

    /**
     * Calling {@link android.database.sqlite.SQLiteDatabase#insert(String, String, android.content.ContentValues)} to
     * persist the current model.
     *
     * @param baseObj Current model to persist.
     * @param values  To store data of current model for persisting.
     * @return The row ID of the newly inserted row, or -1 if an error occurred.
     */
    private long saving(DataSupport baseObj, ContentValues values) {
        return mDatabase.insert(baseObj.getTableName(), null, values);
    }

    /**
     * After the model is saved, do the extra work that need to do.
     *
     * @param baseObj         Current model that is persisted.
     * @param supportedFields List of all supported fields.
     * @param id              The current model's id.
     */
    private void afterSave(DataSupport baseObj, List<Field> supportedFields, long id) {
        throwIfSaveFailed(id);
        assignIdValue(baseObj, getIdField(supportedFields), id);
        updateAssociatedTableWithFK(baseObj);
        insertIntermediateJoinTableValue(baseObj, false);
    }

    /**
     * When a model is associated with two different models.
     *
     * @param baseObj The class of base object.
     * @throws java.lang.reflect.InvocationTargetException
     * @throws IllegalAccessException
     * @throws NoSuchMethodException
     * @throws IllegalArgumentException
     * @throws SecurityException
     */
    private void doUpdateAction(DataSupport baseObj, List<Field> supportedFields)
            throws SecurityException, IllegalArgumentException, NoSuchMethodException,
            IllegalAccessException, InvocationTargetException {
        ContentValues values = new ContentValues();
        beforeUpdate(baseObj, supportedFields, values);
        updating(baseObj, values);
        afterUpdate(baseObj);
    }

    /**
     * Before updating model, it will be analyzed first. Put all the data
     * contained by the model into ContentValues, including the fields value and
     * foreign key value. If the associations between models has been removed.
     * The foreign key value in database should be cleared too.
     *
     * @param baseObj         Current model to update.
     * @param supportedFields List of all supported fields.
     * @param values          To store data of current model for updating.
     * @throws java.lang.reflect.InvocationTargetException
     * @throws IllegalAccessException
     * @throws NoSuchMethodException
     * @throws IllegalArgumentException
     * @throws SecurityException
     */
    private void beforeUpdate(DataSupport baseObj, List<Field> supportedFields, ContentValues values)
            throws SecurityException, IllegalArgumentException, NoSuchMethodException,
            IllegalAccessException, InvocationTargetException {
        putFieldsValue(baseObj, supportedFields, values);
        putForeignKeyValue(values, baseObj);
        for (String fkName : baseObj.getListToClearSelfFK()) {
            values.putNull(fkName);
        }
    }

    /**
     * Calling
     * {@link android.database.sqlite.SQLiteDatabase#update(String, android.content.ContentValues, String, String[])} to
     * update the current model.
     *
     * @param baseObj Current model to update.
     * @param values  To store data of current model for updating.
     */
    private void updating(DataSupport baseObj, ContentValues values) {
        mDatabase.update(baseObj.getTableName(), values, "id = ?",
                new String[]{String.valueOf(baseObj.getBaseObjId())});
    }

    /**
     * After the model is updated, do the extra work that need to do.
     *
     * @param baseObj Current model that is updated.
     */
    private void afterUpdate(DataSupport baseObj) {
        updateAssociatedTableWithFK(baseObj);
        insertIntermediateJoinTableValue(baseObj, true);
        clearFKValueInAssociatedTable(baseObj);
    }

    /**
     * Get the id field by the passed in field list.
     *
     * @param supportedFields The field list to find from.
     * @return The id field. If not found one return null.
     */
    private Field getIdField(List<Field> supportedFields) {
        for (Field field : supportedFields) {
            if (isIdColumn(field.getName())) {
                return field;
            }
        }
        return null;
    }

    /**
     * If the model saved failed, throw an exception.
     *
     * @param id The id returned by SQLite. -1 means saved failed.
     */
    private void throwIfSaveFailed(long id) {
        if (id == -1) {
            throw new DataSupportException(DataSupportException.SAVE_FAILED);
        }
    }

    /**
     * Assign the generated id value to the model. The
     * {@link org.litepal.crud.DataSupport#baseObjId} will be assigned anyway. If the model has a
     * field named id or _id, LitePal will assign it too. The
     * {@link org.litepal.crud.DataSupport#baseObjId} will be used as identify of this model for
     * system use. The id or _id field will help developers for their own
     * purpose.
     *
     * @param baseObj Current model that is persisted.
     * @param idField The field of id.
     * @param id      The value of id.
     */
    private void assignIdValue(DataSupport baseObj, Field idField, long id) {
        try {
            giveBaseObjIdValue(baseObj, id);
            if (idField != null) {
                giveModelIdValue(baseObj, idField.getName(), idField.getType(), id);
            }
        } catch (Exception e) {
            throw new DataSupportException(e.getMessage());
        }
    }

    /**
     * After saving a model, the id for this model will be returned. Assign this
     * id to the model's id or _id field if it exists.
     *
     * @param baseObj The class of base object.
     * @param idName  The name of id. Only id or _id is valid.
     * @param idType  The type of id. Only int or long is valid.
     * @param id      The value of id.
     * @throws SecurityException
     * @throws NoSuchFieldException
     * @throws IllegalArgumentException
     * @throws IllegalAccessException
     */
    private void giveModelIdValue(DataSupport baseObj, String idName, Class<?> idType, long id)
            throws SecurityException, NoSuchFieldException, IllegalArgumentException,
            IllegalAccessException {
        if (shouldGiveModelIdValue(idName, idType, id)) {
            Object value = null;
            if (idType == int.class || idType == Integer.class) {
                value = (int) id;
            } else if (idType == long.class || idType == Long.class) {
                value = id;
            } else {
                throw new DataSupportException(DataSupportException.ID_TYPE_INVALID_EXCEPTION);
            }
            DynamicExecutor.setField(baseObj, idName, value, baseObj.getClass());
        }
    }

    /**
     * If the table for this model have a foreign key column, the value of
     * foreign key id should be saved too.
     *
     * @param values The instance of ContentValues to put foreign key value.
     */
    private void putForeignKeyValue(ContentValues values, DataSupport baseObj) {
        Map<String, Long> associatedModelMap = baseObj.getAssociatedModelsMapWithoutFK();
        for (String associatedTableName : associatedModelMap.keySet()) {
            values.put(getForeignKeyColumnName(associatedTableName),
                    associatedModelMap.get(associatedTableName));
        }
    }

    /**
     * Update the foreign keys in the associated model's table.
     *
     * @param baseObj Current model that is persisted.
     */
    private void updateAssociatedTableWithFK(DataSupport baseObj) {
        Map<String, Set<Long>> associatedModelMap = baseObj.getAssociatedModelsMapWithFK();
        ContentValues values = new ContentValues();
        for (String associatedTableName : associatedModelMap.keySet()) {
            values.clear();
            String fkName = getForeignKeyColumnName(baseObj.getTableName());
            values.put(fkName, baseObj.getBaseObjId());
            Set<Long> ids = associatedModelMap.get(associatedTableName);
            if (ids != null && !ids.isEmpty()) {
                mDatabase.update(associatedTableName, values, getWhereOfIdsWithOr(ids), null);
            }
        }
    }

    /**
     * When the associations breaks between current model and associated models,
     * clear all the associated models' foreign key value if it exists.
     *
     * @param baseObj Current model that is persisted.
     */
    private void clearFKValueInAssociatedTable(DataSupport baseObj) {
        List<String> associatedTableNames = baseObj.getListToClearAssociatedFK();
        for (String associatedTableName : associatedTableNames) {
            String fkColumnName = getForeignKeyColumnName(baseObj.getTableName());
            ContentValues values = new ContentValues();
            values.putNull(fkColumnName);
            String whereClause = fkColumnName + " = " + baseObj.getBaseObjId();
            mDatabase.update(associatedTableName, values, whereClause, null);
        }
    }

    /**
     * Insert values into intermediate join tables for self model and associated
     * models.
     *
     * @param baseObj  Current model that is persisted.
     * @param isUpdate The current action is update or not.
     */
    private void insertIntermediateJoinTableValue(DataSupport baseObj, boolean isUpdate) {
        Map<String, Set<Long>> associatedIdsM2M = baseObj.getAssociatedModelsMapForJoinTable();
        ContentValues values = new ContentValues();
        for (String associatedTableName : associatedIdsM2M.keySet()) {
            String joinTableName = getIntermediateTableName(baseObj, associatedTableName);
            if (isUpdate) {
                mDatabase.delete(joinTableName, getWhereForJoinTableToDelete(baseObj),
                        new String[]{String.valueOf(baseObj.getBaseObjId())});
            }
            Set<Long> associatedIdsM2MSet = associatedIdsM2M.get(associatedTableName);
            for (long associatedId : associatedIdsM2MSet) {
                values.clear();
                values.put(getForeignKeyColumnName(baseObj.getTableName()), baseObj.getBaseObjId());
                values.put(getForeignKeyColumnName(associatedTableName), associatedId);
                mDatabase.insert(joinTableName, null, values);
            }
        }
    }

    /**
     * Get the where clause to delete intermediate join table's value for
     * updating.
     *
     * @param baseObj Current model that is persisted.
     * @return The where clause to execute.
     */
    private String getWhereForJoinTableToDelete(DataSupport baseObj) {
        StringBuilder where = new StringBuilder();
        where.append(getForeignKeyColumnName(baseObj.getTableName()));
        where.append(" = ?");
        return where.toString();
    }

    /**
     * Judge should assign id value to model's id field. The principle is that
     * if id name is not null, id type is not null and id is greater than 0,
     * then should assign id value to it.
     *
     * @param idName The name of id field.
     * @param idType The type of id field.
     * @param id     The value of id.
     * @return If id name is not null, id type is not null and id is greater
     * than 0, return true. Otherwise return false.
     */
    private boolean shouldGiveModelIdValue(String idName, Class<?> idType, long id) {
        return idName != null && idType != null && id > 0;
    }
}
